Work in progress cranelift codegen backend for rust

⚠⚠⚠ This doesn't do anything useful yet ⚠⚠⚠

Building

$ git clone https://github.com/bjorn3/rustc_codegen_cranelift.git
$ cd rustc_codegen_cranelift
$ rustup override set nightly
$ git submodule update --init
$ cargo build

Usage

$ rustc -Zcodegen-backend=$(pwd)/target/debug/librustc_codegen_cranelift.so my_crate.rs --crate-type lib -Og

Building libcore

$ rustup component add rust-src
$ ./prepare_libcore.sh
$ ./build.sh

⚠⚠⚠ You will get a panic because of unimplemented stuff ⚠⚠⚠

Not yet supported

• Checked binops

• Statics

• Drop glue

• Building libraries

• Other call abi's

• Unsized types

• Slice indexing

• Sub slice

• Some rvalue's

• Inline assembly

• Custom sections

Known errors

• cranelift-module api seems to be used wrong, thus causing panic for some consts
• cranelift-codegen doesn't have encodings for some instructions for types smaller than I32

[...]
warning: DefId(0/0:128 ~ lib[8787]::f64[0]::{{impl}}[0]::classify[0]):
fn f64::<impl at ./target/libcore/src/libcore/num/f64.rs:156:1: 490:2>::classify(_1: f64) -> num::FpCategory{
[...]
}
warning: stmt _3 = _1
warning: stmt _5 = BitAnd(move _6, const Unevaluated(DefId(0/0:130 ~ lib[8787]::f64[0]::{{impl}}[0]::classify[0]::MAN_MASK[0]), []):u64)
thread 'main' panicked at 'called `Option::unwrap()` on a `None` value', libcore/option.rs:345:21
stack backtrace:
[...]
  10: <core::option::Option<T>>::unwrap
             at /checkout/src/libcore/macros.rs:20
  11: rustc_codegen_cranelift::constant::trans_constant
             at src/constant.rs:26
[...]